Unidrive M / Unidrive HS Modular Installation Guide
107
Issue Number: 5
3. The total power rating must not be less than the maximum expected
regenerative power.
4. If the DC buses are separate and the modules are all the same
rating, the brake resistors must match to better than 5% at all power
flows. (If the temperature coefficient and/or temperature rise of the
resistor is significant then the cooling must also match to ensure the
resistors are at similar temperatures and hence similar resistance
values.)
5. If the DC buses are common the brake resistors do not need to
match. However to use the drive's brake resistor protection
algorithm it must be set up to protect the most vulnerable resistor.
6.12 Ground leakage
The ground leakage current depends upon whether the internal EMC
filter is installed. The drive is supplied with the filter installed.
With internal filter installed:
56 mA AC at 400 V 50 Hz (proportional to supply voltage and
frequency)
18 µA DC with a 600 V DC bus (33 M
Ω
)
With internal filter removed*:
<1mA
Note that in both cases there is an internal voltage surge protection
device connected to ground. Under normal circumstances this carries
negligible current.
*Please note that the internal filter is not removable on size 9E/T, 10E/T
and 11E/T.
6.12.1 Use of residual current device (RCD)
There are three common types of ELCB / RCD:
1.
AC - detects AC fault currents
2. A - detects AC and pulsating DC fault currents (provided the DC
current reaches zero at least once every half cycle)
3. B - detects AC, pulsating DC and smooth DC fault currents
•
Type AC should never be used with drives.
•
Type A can only be used with single phase drives
•
Type B must be used with three phase drives
If an external EMC filter is used, a delay of at least 50 ms should be
incorporated to ensure spurious trips are not seen. The leakage current
is likely to exceed the trip level if all of the phases are not energized
simultaneously.
When the internal filter is installed the leakage current is
high. In this case a permanent fixed ground connection must
be provided, or other suitable measures taken to prevent a
safety hazard occurring if the connection is lost
.
Only type B ELCB / RCD are suitable for use with 3 phase
inverter drives.
WARNING
WARNING
WARNING
WARNING
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